RIVETING APPARATUS

APPAREIL A RIVER

English Abstract

A hand-held riveting tool is driven by
a battery-powered electric motor (26), and comprises
a hydraulically-actuated riveting head (11), and a re-
ciprocating hydraulic pump (22) driven by the elec-
tric motor. The tool includes a reservoir (23) for hy-
draulic fluid, the hydraulic supply line from the pump
to the riveting head (11) being connected to the reser-
voir (23) by a reservoir inlet valve (29) which is nor-
mally open to allow hydraulic fluid to flow from the
supply line into the reservoir (23). Operation of the
tool-actuating trigger (31) firstly closes the reservoir
inlet valve (29), and then switches on the electric mo-
tor (26) to operate the pump (22). Release of the tool-
actuating trigger (31) firstly switches off the electric
motor (26) to stop operation of the pump (22), and
then opens the reservoir inlet valve (29). When the
reservoir inlet valve (29) is closed by operation of the
trigger (31), it acts as a pressure-relief valve to relieve
over-pressure of hydraulic fluid.

French Abstract

La présente invention concerne un outil à river portatif entraîné par un moteur électrique (26) alimenté par batterie, qui comprend une tête de rivetage hydraulique (11) et une pompe hydraulique alternative (22) entraînée par le moteur électrique. L'outil de l'invention comprend un réservoir de liquide hydraulique (23), la conduite d'alimentation hydraulique reliant la pompe à la tête de rivetage (11) étant raccordée au réservoir (23) par une soupape d'admission (29) du réservoir qui est normalement ouverte afin de permettre l'écoulement du liquide hydraulique depuis la conduite d'alimentation jusque dans le réservoir (23). Lorsque l'on actionne la gâchette (31) qui commande l'outil, on entraîne d'abord la fermeture de la soupape d'admission (29) du réservoir, et ensuite la mise en marche du moteur électrique (26) qui actionne la pompe (22). Lorsque l'on relâche la gâchette (31) qui commande l'outil, on entraîne d'abord l'arrêt du moteur électrique (26) qui arrête le fonctionnement de la pompe (22), et ensuite l'ouverture de la soupape d'admission (29) du réservoir. Lorsque la soupape d'admission (29) du réservoir se ferme sous l'action de la gâchette (31), elle agit comme une soupape de décharge qui réduit la surpression du liquide hydraulique.

Claims

7
CLAIMS
1. A hand-held riveting tool driven by a battery-powered electric motor,
comprising a
hydraulically-actuated riveting head, and a hydraulic pump driven by the
electric motor,
whereby, upon operation, the motor drives the hydraulic pump to actuate the
riveting head,
the tool including a tool-actuating device, and also including a reservoir for
hydraulic fluid, a
hydraulic supply line from the pump to the riveting head being connected to
the reservoir by a
reservoir inlet valve which is normally open to allow the hydraulic fluid to
flow from the
hydraulic supply line into the reservoir, in which operation of the tool-
actuating device first
closes the reservoir inlet valve, and then switches on the electric motor to
operate the pump.
2. A riveting tool as claimed in claim 1, in which release of the tool-
actuating device first
switches off the electric motor to stop operation of the pump, and then opens
the reservoir
inlet valve.
3. A riveting tool as claimed in claim 1 or claim 2, in which the reservoir
inlet valve
when closed by operation of the tool-actuating device as aforesaid also acts
as a pressure-
relief valve to relieve over-pressure of hydraulic fluid.
4. A riveting tool as claimed in claim 3 in which the reservoir inlet valve is
urged closed
by a first spring with a first predetermined force and is urged open by a
second spring with a
second predetermined force, operation of the tool-actuating device removing
the action of the
second predetermined force, whereby the valve is thereafter held closed by the
first
predetermined force regardless of sustained operation of the tool-actuating
device, thereby to
provide a predetermined pressure at which the valve acts as a pressure relief
valve as
aforesaid.

8
5. A riveting tool as claimed in any one of the claims 1 to 4, in which the
riveting head is
adapted to place blind breakstem rivets.
6. A riveting tool as claimed in any one of claims 1 to 5, in which after the
motor has
been operated to actuate the riveting head as aforesaid and is then switched
off, the riveting
head is returned to its initial position by means independent of the motor.
7. A riveting tool as claimed in claim 6, in which the head is returned to its
initial
position by means of a spring.
8. A riveting tool as claimed in any one of claims 1 to 7, in which the
electric motor, in
use, rotates in only one direction.
9. A riveting tool as claimed in any one of claims 1 to 8, in which the
hydraulic pump is
a reciprocating pump.
10. A riveting tool as claimed in any one of claims 1 to 9, wherein said tool-
actuating
device is a trigger.

Description

CA 02385934 2006-09-26
1
RIVETING APPARATUS
The present invention relates to riveting apparatus, and more particularly to
hand-held
riveting apparatus of the type in which is driven by a battery-powered
electric motor.
One such form of apparatus is described in US 5 473 805. This is a tool for
riveting by
means of blind breakstem rivets of the well-known type in which the rivet is
placed by pulling a
breakable stem with respect to a tubular body. The pulling head includes a
reciprocable element,
which is permanently connected to the electric motor by means of a mechanical
gearbox, the
electric motor being reversible in order to reverse the movement of the
reciprocable element.
Riveting tools according to US 5 473 805 have found acceptance in industry,
but however they
have the disadvantage of being relatively inefficient.
The present invention aims to allow the design and construction of riveting
apparatus
which is more efficient.
The invention provides, in one of its aspects, a hand-held riveting tool
driven by a
battery-powered electric motor comprising a hydraulically-actuated riveting
head and a hydraulic
pump driven by the electric motor whereby, upon operation, the motor drives
the hydraulic pump
to actuate the riveting head. The tool includes a tool-actuating device and
also includes a
reservoir for hydraulic fluid. A hydraulic supply line from the pump to the
riveting head is
connected to the reservoir by a reservoir inlet valve which is normally open
to allow the
hydraulic fluid flow from the hydraulic supply line into the reservoir.
Operation of the tool-
actuating device first closes the reservoir inlet valve, and then switches on
the electric motor to
operate the pump.
A specific embodiment of the invention will be described by way of example and
with
reference to the accompanying drawings, in which:
Figure 1 is a section through a hand-held battery-powered breakstem blind
riveting tool;
Figure 2 is an enlargement of part of Figure 1;
Figure 3 is a view on the line III of Figure 1;

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Figures 4A, 4B and 4C show progressive positions of the reservoir inlet
valve;
Figure 5 is an enlarged, partly sectional, view in the direction of the arrow
V
in Figure 1; and
Figure 6 is a schematic block diagram of the hydraulic circuitry of the tool.
The hand-held tool of this example is conventional in its general layout. It
includes a breakstem riveting head 11 with an annular nosetip anvil 12 for
supporting
the shell head of a blind breakstem rivet (such as that available in many
countries
under the Registered Trade Mark AVEX), the protruding stem of which is gripped
by
reciprocable jaws (not shown) carried by the forward end of a reciprocable
drawbar
13. The rear end of the drawbar is connected to a head piston 14 reciprocable
in a
hydraulic cylinder 15. The piston 14 is actuated to place a rivet by supplying
hydraulic fluid under pressure to the cylinder space 16 in front of the
piston. After
placing of a rivet the piston is returned forwardly by a spring 17. A suitable
receptacle (not shown) may be attached to the rear end 21 of the head, to
receive
broken-off parts of rivet stems. The operation of the riveting head 11 is
conventional.
The tool includes a reciprocating hydraulic pump 22 and a reservoir 23 for
hydraulic fluid. The pump is operated by an eccentric cam 24, which is
rotated,
through a reduction gearbox 25, by means of an electric motor 26. When the
pump
is operated it draws hydraulic fluid from the reservoir 23 through an inlet
non-return
valve 27, and supplies hydraulic fluid to the riveting head 11 through an
outlet non-
return valve 28. A further trigger-operated reservoir inlet valve 29 is also
connected,
SUBSTITUTE SHEET (RULE 26)

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as shown in Figure 6, betweert the outlet side of the outlet non-return valve
28 and
the reservoir 23.
The reservoir inlet valve 29 is normally open so that it allows hydraulic
fluid
to flow from the head space 16, to the reservoir 23. The valve 29 is closed by
actuation of a trigger 31 which is pivoted at 32 to the body of the tool, and
carries a
pair of projections 33 which contact the valve 29 in order to actuate it.
Mounted adjacent the trigger-operated valve 29 is an electrical switch 34
(Figure 4), which is connected by means of electrical wiring (not shown) to
actuate a
relay 35 to connect a battery 36, housed at the bottom end of the pistol grip
18, to
actuate the motor 26 to drive the pump 22.
The arrangement of the trigger 31, valve 29 and switch 34 is such that, when
the trigger 31 is progressively depressed by progressively increasing force
from the
finger of an operator grasping the pistol grip 18, firstly the valve 29 is
closed,
thereby preventing flow of hydraulic fluid into the reservoir 23, and
thereafter the
switch 34 is closed, thereby starting the electric motor 26 and the pump 22.
When
the trigger 31 is released, firstly the switch 34 opens to shut off the
electric motor 26
and pump 22, and thereafter the valve 29 is opened. Moreover, it is arranged
that
during the time when the valve 29 is closed as just described, nonetheless it
can still
operate as a pressure relief valve to relieve into the reservoir any
dangerously high
pressure of hydraulic fluid which may build up. As previously mentioned, the
switch
34 is mounted adjacent the valve 29, so that the actuating button 37 of the
switch
(see Figure 4) is actuated by a moving part of the valve 29 which is moved by
operation of the trigger 31.
SUBSTITUTE SHEET (RULE 26)

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Figure 4 shows the construction and operation of the valve 29. It comprises a
generally cylindrical tubular body 38 in which can reciprocate a generally
cylindrical
valve member 39. In the top end wal141 of the valve body 38 is a circular
inlet port
42, which can be closed by means of a conical projection 43 at the top of the
valve
member 39. When the inlet port 42 is open it communicates with a lateral
outlet 44
to allow hydraulic fluid into the reservoir 23. Around the lower part of the
valve
member 39 is a sleeve 45, the lower end of which protrudes from the valve body
38
and bears against a washer 46 held on to the lower end of the valve member 39
by a
circlip 47. The lower end of the sleeve 45 is enlarged into a flange 51 which
has a
transverse extension in the form of a lug 52 (Figure 5). The trigger
projections 33
contact the underside of the sleeve flange 51, and the projecting lug 52 is
aligned
under the switch 34 so that the lug can contact the switch button 37 to
actuate the
switch, as will be described later.
The valve member 39 is urged upwardly into the closed position by means of
a first helical spring 48 acting between the valve body 29 and the upper end
of the
valve member 39. It is urged downwardly into the open position by means of a
second helical spring 49, acting between the valve body 29 and the sleeve 45,
and
thereby through the washer 46 and circlip 47 on the valve member 39.
The two springs 48 & 49 are identical, so that the valve member 39 is
normally held "floating" in the open position, as shown in Figure 4A. Figures
4A,
4B and 4C are aligned vertically with each other to illustrate the relative
positions of
the sleeve 45, valve member 39 and trigger 31 at different stages in the
progressive
operation of the trigger 31. Figure 4 also illustrates the relative vertical
alignment
SUBSTITUTE SHEET (RULE 26)

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(but not the horizontal alignment) of the switch 34 and its button 37. Figure
4A
shows the position with the trigger 31 not operated, i.e. in its rest
position; the
sleeve 45 is held in its lowest position by the second spring 49, and the
valve
member 39 is in its lowest or open position, as explained above, and the
switch 34 is
5 not actuated, i.e. it is in its "off' position.
When the operator actuates the trigger by applying a progressively increasing
force to it, the projections 33 bear on the flange 51 of the sleeve 45, to
push it
upwards, thus progressively compressing the second spring 49 and allowing the
first
spring 48 to progressively push the valve member upwards, towards its closed
position. Figure 4B illustrates the valve member 39 in its fully closed
position, with
the conical projection 43 sealing the inlet part 42 under the urging of the
first spring
47. The switch 34 is still not actuated, i.e. it is still in its "off"
position.
As the operator applies still more force to the trigger 31, the projections 33
apply more force to the bottom of the sleeve 45, and lifts the sleeve 45 out
of contact
with the washer 46, whilst compressing the second spring 49 even further. When
the
sleeve 45 has left contact with the washer 46, the second spring 49 no longer
has any
effect in reducing the closing force exerted by the first spring 48 on the
valve
member 39. Hence the closing force on the valve is a predetermined known
value,
so that the valve will operate as a pressure relief valve at a predetermined
over-
pressure of the hydraulic fluid. This will allow hydraulic fluid to be safely
returned
to the reservoir 23, regardless of sustained operation of the tool -actuating
device,
i.e. if the operator keeps the trigger 31 depressed for a long time so that
the head
piston 14 contacts the cylinder cap.
SUBSTITUTE SHEET (RULE 26)

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As the sleeve 49 continues to rise in this way, its projecting lug 52 actuates
the button 37 of the switch 34. This starts the electric motor 26, which
operates the
pump 22. This applies hydraulic fluid under pressure to the space 16 on the
pulling
head 11, thus actuating the head mechanism to place a rivet, the drawbar 13
being
retracted against the urging of spring 17. When the rivet has been placed, the
operator releases the force on the trigger 3 1. The sequence of movements
described
above is reversed. Firstly the sleeve 45 descends, allowing the switch 34 to
turn off
and stop the pump 28. Then the valve member 39 is allowed to move away from
the
inlet part 42, thus allowing hydraulic fluid to be ejected from the head
cylinder space
16 by piston 14 under the urging of spring 17, and into the reservoir 23. The
piston
14, drawbar 13 and the riveting head are thus returned to their initial
positions by the
spring 17, and not by the electric motor 26. Thus the electric motor, in use,
rotates in
only one direction. The valve 29 returns to its rest position illustrated in
Figure 4A.
It is found that a battery-operated hand-held riveting tool as described above
is substantially more efficient than the prior art tool referred to in the
preamble due
to the conversion of rotary motion to linear motion by hydraulic means instead
of
mechanical means, and the use of a uni-directional electric motor, i.e. one
which is
electrically actuated so as to rotate in only one direction, i.e. to actuate
the riveting
head, but not to return the riveting head its initial position.
The invention is not restricted to the details of the foregoing example. For
instance, it could be applied to a tool for a form of riveting, other than
blind
breakstem riveting, e.g. blind repetition pull-through riveting, the
installation of
threaded inserts, or self-piercing riveting.
SUBSTITUTE SHEET (RULE 26)

Representative Drawing